JP2012032344A - Picture measuring device, picture measuring method and program for picture measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture measuring device capable of readily identifying degrees of contour inconsistency with respect to a plurality of works.SOLUTION: A picture measuring device comprises: edge extracting means that extracts edges from a work picture A2; picture comparing means that compares the work picture A2 with a master picture A1 held in advance; error calculating means that calculates errors indicating amounts of displacement between the edge positions on the work picture A2 and positions on the master picture A1 corresponding to these edge positions; statistical information calculating means that calculates for each edge position statistical information on errors calculated for a plurality of work pictures A2; and statistical information displaying means that displays the statistical information along the extracted edge positions extracted from the work pictures A2 or the master picture A1 in a displaying mode corresponding to the value of the statistical information.

Description

  The present invention relates to an image measuring apparatus, an image measuring method, and a program for the image measuring apparatus. More specifically, the present invention relates to an image measuring apparatus that measures the dimensions of a workpiece based on the edge position of a workpiece image obtained by photographing the workpiece. About.

  In general, an image measuring apparatus is an apparatus that captures a workpiece to acquire a workpiece image and measures the dimension of the workpiece based on the edge position of the workpiece image, and is sometimes called an image measuring instrument (for example, Patent Document 1). To 3). Usually, the workpiece is placed on a movable stage movable in the X, Y and Z axis directions. The workpiece image is focused by moving the movable stage in the Z-axis direction, and the position of the workpiece in the field of view is adjusted by moving in the X- and Y-axis directions.

  The workpiece image is a very accurate similar shape to the workpiece regardless of the position of the movable stage in the Z-axis direction, so the actual dimensions on the workpiece are detected by determining the distance and angle on the image. can do. In measuring the dimensions of a workpiece, edge extraction of the workpiece image is performed. Edge extraction is performed by analyzing the brightness change of the workpiece image, detecting edge points, and fitting a geometric figure such as a straight line or arc to the detected edge points to indicate the boundary between the workpiece and the background Edge is required.

  In a conventional image measuring apparatus, a workpiece image is compared with a predetermined master image held in advance, an error indicating an amount of displacement between the edge position of the workpiece image and a corresponding position on the master image is obtained, and the obtained error is calculated. There are some which judge the quality of a contour by comparing with an allowable error. Such a conventional image measuring apparatus measures a plurality of workpieces sequentially to obtain dimensional values such as distance and angle for quality control of the same type of workpieces manufactured through the same manufacturing process. With respect to the workpiece, the average value and dispersion value of the dimension values can be obtained and displayed.

JP 2009-300124 A JP 2009-300125 A JP 2010-19667 A

  The present invention has been made in view of the above circumstances, and provides an image measurement device, an image measurement method, and a program for the image measurement device that can easily identify the degree of inconsistency of contours for a plurality of workpieces. For the purpose. In particular, it is an object of the present invention to provide an image measuring apparatus that can easily identify statistical information regarding an edge position error for an arbitrary point on an edge extracted from a workpiece image or a master image.

  An image measuring apparatus according to a first aspect of the present invention is an image measuring apparatus that captures an image of a workpiece, acquires the workpiece image, and measures the dimension of the workpiece based on the edge position of the workpiece image. Edge extracting means for extracting the workpiece image, image comparing means for comparing the workpiece image and pre-stored design data, and the edge position of the workpiece image and the design data corresponding to the edge position based on the comparison result An error calculating means for calculating an error indicating a displacement amount with respect to the position, a statistical information calculating means for calculating statistical information of the error calculated for a plurality of the work images for each edge position, and the statistical information, Statistical information display means for displaying along the edge position extracted from the work image or the design data in a display mode according to the value. .

  According to such a configuration, for a plurality of work images, the statistical information of the error between the edge position of the work image and the corresponding position on the design data is calculated for each edge position, and displayed along the edge position. Error statistics can be easily identified for any point on the edge. That is, since statistical information of errors obtained from multiple workpiece images is displayed along the edge position, it is possible to intuitively understand where statistical information indicates statistical information in the workpiece image. it can. Therefore, it is possible to easily identify the degree of contour mismatch for a plurality of workpieces. For example, when a reduction in machining accuracy occurs locally, it is possible to intuitively grasp a place where the machining accuracy is lowered.

  In addition to the above configuration, the image measuring apparatus according to the second aspect of the present invention further includes statistical information designating means for designating the statistical information to be displayed. The statistical information calculating means uses the error information as the statistical information. The statistical value display means is designated by calculating the average value, the variance value of the error, the rate at which the error is less than the allowable error, the rate at which the error exceeds the allowable error, or the slope of the moving average of the error. The statistical information is displayed along the edge position. According to such a configuration, the statistical information to be displayed along the edge position can be switched as necessary.

  An image measuring apparatus according to a third aspect of the present invention includes edge position designating means for designating an edge position on the work image or the design data in addition to the above-described configuration, and the statistical information display means includes the designated edge. The time-series information including the error for each work image corresponding to the position is displayed. According to such a configuration, by specifying the edge position, it is possible to confirm time series information of errors associated with the specified edge position.

  In addition to the above configuration, the image measurement apparatus according to the fourth aspect of the present invention is configured such that the statistical information display unit displays dots of different colors along the edge position according to the value of the statistical information. According to such a configuration, error statistical information can be easily identified by the color of a dot.

  In addition to the above configuration, the image measurement apparatus according to the fifth aspect of the present invention is configured such that the statistical information display means displays dots having different sizes along the edge positions according to the value of the statistical information. . According to such a configuration, error statistical information can be easily identified by the size of the dots.

  In addition to the above-described configuration, the image measuring apparatus according to the sixth aspect of the present invention is configured such that the statistical information display means displays a histogram having different heights along the edge position according to the value of the statistical information. . According to such a configuration, error statistical information can be easily identified by the height of the histogram.

  An image measurement method according to a seventh aspect of the present invention is an image measurement method for capturing a workpiece and acquiring a workpiece image, and measuring the dimension of the workpiece based on an edge position of the workpiece image. An edge extraction step for extracting the workpiece image, an image comparison step for comparing the workpiece image and pre-stored design data, and an edge position of the workpiece image and the design data corresponding to the edge position based on the comparison result An error calculating step for calculating an error indicating a displacement amount with respect to the position of the position, a statistical information calculating step for calculating statistical information of the error calculated for a plurality of the work images for each edge position, and the statistical information, Statistical information display step for displaying along the edge position extracted from the work image or the design data in a display mode according to the value. Consisting of.

  A program for an image measuring device according to an eighth aspect of the present invention is a program for an image measuring device for capturing a workpiece, obtaining a workpiece image, and measuring the dimension of the workpiece based on an edge position of the workpiece image. An edge extraction procedure for extracting an edge from the workpiece image, an image comparison procedure for comparing the workpiece image and pre-stored design data, and an edge position of the workpiece image and the edge based on the comparison result An error calculation procedure for calculating an error indicating an amount of displacement from the position on the design data corresponding to the position, and a statistical information calculation procedure for calculating statistical information on the error calculated for a plurality of the work images for each edge position And the statistical information is displayed along the edge position extracted from the work image or the design data in a display mode according to the value. To perform a total of information display procedure.

  In the image measurement apparatus, the image measurement method, and the program for the image measurement apparatus according to the present invention, statistical information on errors between the edge position of the work image and the corresponding position on the design data is calculated for each edge position for a plurality of work images. Since it is displayed along the edge position, the error statistical information can be easily identified for any point on the edge. Therefore, it is possible to easily identify the degree of contour mismatch for a plurality of workpieces.

It is the perspective view which showed one structural example of the image measuring apparatus 100 by embodiment of this invention. FIG. 2 is an explanatory diagram schematically showing a configuration example in the measurement unit 10 in the image measurement apparatus 100 of FIG. 1, and shows a state of a cut surface by a vertical surface of the measurement unit 10. 3 is a flowchart illustrating an example of the operation of the image measurement apparatus 100 in FIG. 1. 3 is a flowchart illustrating an example of an operation when creating measurement setting data in the image measurement apparatus 100 of FIG. 1. 3 is a flowchart illustrating an example of an operation at the time of measurement in the image measurement apparatus 100 in FIG. 1. It is the figure which showed an example of master image A1 previously hold | maintained as design data. It is the figure which showed an example of the operation | movement at the time of the display of the measurement result in the image measuring apparatus 100 of FIG. 1, and shows an example of the graph display of the time series information linked | related with the edge position. It is the figure which showed an example of the operation | movement at the time of the display of the measurement result in the image measurement apparatus of FIG. 1, and the frequency distribution for every measured value linked | related with the edge position is shown. It is the figure which showed an example of the operation | movement at the time of the display of the measurement result in the image measuring apparatus 100 of FIG. 1, and the workpiece | work image A2 by which the dot 1 which shows statistical information is arrange | positioned is shown. It is the figure which showed an example of the operation | movement at the time of the display of the measurement result in the image measuring apparatus 100 of FIG. 1, and the workpiece | work image A2 by which the dot 1 which shows statistical information is arrange | positioned is shown. It is the figure which showed another example of the operation | movement at the time of the display of the measurement result in the image measuring apparatus 100 of FIG. 1, and the case where the dot 1 is thinned and arrange | positioned on the edge is shown. FIG. 2 is a block diagram illustrating a configuration example of a control unit 20 in the image measurement apparatus 100 of FIG. 1, in which an example of a functional configuration in the control unit 20 is illustrated. 3 is a flowchart illustrating an example of an operation when displaying statistical information in the image measurement apparatus 100 of FIG. 1.

<Image measuring device>
FIG. 1 is a perspective view showing a configuration example of an image measuring apparatus 100 according to an embodiment of the present invention. The image measuring apparatus 100 is a measuring instrument that photographs a plurality of workpieces arranged in a detection area 13 on a movable stage 12 at different imaging magnifications, analyzes the captured images, and automatically measures the dimensions of each workpiece. , Measuring unit 10, control unit 20, keyboard 31 and mouse 32. The workpiece is a measurement object whose shape and dimensions are measured.

  The measurement unit 10 is an optical system unit that irradiates a workpiece with detection light and receives the transmitted light or reflected light to generate a photographed image. The display unit 11, the movable stage 12, the XY position adjustment knob 14a, and the Z position adjustment. A knob 14b, a power switch 15 and a measurement start switch 16 are provided.

  The display 11 is a display device that displays captured images and measurement results on the display screen 11a. The movable stage 12 is a mounting table for mounting a workpiece to be measured, and is provided with a detection area 13 that transmits detection light. The detection area 13 is a circular area made of transparent glass. The movable stage 12 can be moved in the Z-axis direction parallel to the optical axis of the detection light and the XY axial directions perpendicular to the optical axis.

  The XY position adjustment knob 14a is an operation unit for moving the movable stage 12 in the X-axis direction and the Y-axis direction. The Z position adjustment knob 14b is an operation unit for moving the movable stage 12 in the Z-axis direction. The power switch 15 is an operation unit for turning on the power of the measurement unit 10 and the control unit 20, and the measurement start switch 16 is an operation unit for starting measurement on the workpiece.

  The control unit 20 is a controller that controls photographing and screen display by the measurement unit 10 and analyzes the photographed image to measure the dimensions of the workpiece, and is connected to a keyboard 31 and a mouse 32. After the power is turned on, if a plurality of works are appropriately arranged in the detection area 13 and the measurement start switch 16 is operated, the dimensions of each work are automatically measured.

<Measurement unit>
FIG. 2 is an explanatory diagram schematically showing a configuration example in the measurement unit 10 in the image measurement apparatus 100 of FIG. 1, and shows a state of a cut surface when the measurement unit 10 is cut along a vertical plane. . The measurement unit 10 includes a housing 40 having a Z driving unit 41, an XY driving unit 42, imaging elements 43 and 44, a transmission illumination unit 50, a ring illumination unit 60, a coaxial incident illumination light source 71, and a light receiving lens unit 80. It is configured.

  The Z drive unit 41 is a Z position adjusting unit that moves the movable stage 12 in the Z axis direction based on a drive signal from the control unit 20 to adjust the position of the workpiece in the Z axis direction. The XY drive unit 42 is an XY position adjusting unit that adjusts the position of the workpiece in the XY plane by moving the movable stage 12 in the X-axis direction and the Y-axis direction based on the XY drive signal from the control unit 20.

  The transmitted illumination unit 50 is an illumination device for irradiating the work placed on the movable stage 12 with detection light from below, and includes a transmitted illumination light source 51, a mirror 52, and an optical lens 53. The detection light emitted from the transmission illumination light source 51 is reflected by the mirror 52 and emitted through the optical lens 52. The detection light passes through the movable stage 12, a part of the transmitted light is blocked by the work, and the other part enters the light receiving lens unit 80.

  The ring illumination unit 60 is an illumination device for irradiating the workpiece on the movable stage 12 with detection light from above, and includes a ring-shaped light source surrounding the light receiving lens unit 80. The coaxial epi-illumination light source 71 is a light source for irradiating the workpiece on the movable stage 12 with detection light from above, and the optical axis of the irradiation light to the workpiece and the optical axis of the reflected light from the workpiece are coaxial. Thus, the half mirror 72 is arranged. As a method for illuminating the workpiece, one of transmission illumination, ring illumination, and coaxial epi-illumination can be selectively switched.

  The light receiving lens unit 80 is an optical system including the light receiving lenses 81, 84, 86, the half mirror 82, and the diaphragm plates 83 and 85, and receives the transmitted light from the transmitted illumination unit 50 and the reflected light of the detection light by the work. Then, an image is formed on the image sensors 43 and 44. The light receiving lens 81 is an optical lens disposed on the movable stage 12 side, and is disposed to face the upper surface of the movable stage 12. The light receiving lens 84 is an optical lens disposed on the image sensor 43 side, and is disposed to face the image sensor 43. The light receiving lens 86 is an optical lens disposed on the image sensor 44 side, and is disposed to face the image sensor 44.

  The diaphragm plate 83 and the light receiving lens 84 are low-magnification-side image forming portions having a low photographing magnification, and are arranged such that their central axes coincide with the optical lens 53 and the light receiving lens 81. On the other hand, the diaphragm plate 85 and the light receiving lens 86 are high-magnification side imaging units with high photographing magnification, and detection light from the work is incident through the half mirror 82. The light receiving lenses 81, 84, and 86 have a property that does not change the size of the image even if the position of the workpiece in the optical axis direction (Z-axis direction) changes, and is called a telecentric lens.

  The image sensor 43 is a low-magnification image sensor that captures a low-magnification visual field formed by the light-receiving lens unit 80 and generates a low-magnification image. The image sensor 44 is a high-magnification image sensor that captures a high-magnification field-of-view workpiece formed by the light-receiving lens unit 80 at a high magnification and generates a high-magnification image. The high magnification field is a narrower field than the low magnification field, and is formed in the low magnification field.

  The imaging elements 43 and 44 are each composed of a semiconductor element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).

  In this image measuring apparatus 100, as long as it is within the detection area 13 of the movable stage 12, the work can be captured with a low magnification field of view no matter where it is placed. Further, the work placed in the low magnification field of view is guided into the high magnification field of view by photographing the low magnification image and moving the movable stage 12 in the XY plane, and is photographed at a high magnification. In this image measuring apparatus 100, the low-magnification visual field and the high-magnification visual field are substantially concentric, and a low-magnification image and a high-magnification image can be acquired simultaneously.

<Operation of image measuring apparatus>
Steps S101 to S103 in FIG. 3 are flowcharts showing an example of the operation of the image measurement apparatus 100 in FIG. In this image measuring apparatus 100, the operation consists of three processes, namely, creation of measurement setting data (step S101), execution of measurement (step S102), and display of measurement results (step S103).

  The measurement setting data is information necessary for execution of measurement, and includes feature amount information indicating feature amounts, information indicating measurement locations and measurement types, information indicating design values and tolerances for each measurement location, and the like. The feature amount information is positioning information for analyzing the workpiece image and detecting the position and posture of the workpiece, and is set based on a predetermined master image. If the feature amount information, the information indicating the measurement location and the measurement type are set based on the high-magnification image, identification information indicating that fact is stored as measurement setting data.

  The measurement setting data is created in the control unit 20. Alternatively, the configuration may be such that measurement setting data created in an information processing terminal such as a PC (personal computer) is transferred to the control unit 20 and used. The measurement process is executed based on such measurement setting data. And the display process of a measurement result is performed by displaying the dimension value etc. which were obtained by measurement on the display 11. FIG.

<Create measurement setting data>
Steps S201 to S203 in FIG. 4 are flowcharts showing an example of the operation when creating the measurement setting data in the image measurement apparatus 100 in FIG. This figure shows a case where measurement setting data is created in the control unit 20.

  The measurement setting data creation process includes three processing procedures: design data input (step S201), feature value setting (step S202), and design value and tolerance correction (step S203). In the design data input step, a photographed image obtained by photographing a predetermined reference object such as a master piece or CAD data created by CAD (Computer Aided Design) is input, and contour comparison to be described later is performed from the input design data. It is the step which acquires the outline information. The contour information is a set of edge points of an image obtained by photographing the master piece as design data. When CAD data is used as design data, the design value of the CAD data corresponds to the contour information. .

  When tolerances are set in advance in the input design data for the range in which contour comparison is performed and for each contour to be compared, these pieces of information are also input together with the design data and set as measurement setting data.

  In step S202, the feature amount is automatically extracted from the input design data. However, the feature amount may be set by setting a range in which the user extracts the feature amount.

  Subsequently, in step S203, the user can correct the range or tolerance for performing the contour comparison as necessary. By executing the above steps, the measurement setting data including the contour comparison range of the design data, the contour information within the contour comparison range as the design value, and the tolerance of each contour position is generated and stored.

<Contour comparison>
Steps S301 to S308 in FIG. 5 are flowcharts illustrating an example of an operation at the time of measurement in the image measurement apparatus 100 in FIG. First, the work placed on the movable stage 12 is photographed to obtain a work image, and the work image is analyzed based on the feature amount information of the measurement setting data, thereby positioning the work (step S301). The positioning of the workpiece is performed by detecting the position and orientation of the workpiece in the workpiece image using a method such as pattern matching based on the feature amount information.

  Next, based on the detection result of the position and orientation and the measurement setting data, a range for contour comparison is specified (step S302), and an edge existing in the comparison range is extracted (step S303). As an edge extraction method, a method using the luminance value of the image, a method using the first derivative of the luminance value, a method using the second derivative of the luminance value, or the like can be used.

  Next, each extracted edge position is compared with the outline information (design value) of the design data corresponding to each edge position, and an error is calculated (steps S304 and S305). The error from the design value is calculated geometrically. That is, when the contour information of the design data is given as a curve, the error can be defined as the distance between the edge position and the normal direction of the curve. Further, when the contour information is given as reference coordinates, it can be calculated as a distance in the direction of each coordinate axis of XY.

  Subsequently, the error calculated at this time is compared with the tolerance included in the measurement setting data (step S306), and pass / fail is determined for each edge position (step S307). In this way, by comparing the contour information of the design data inputted in advance with the edge position extracted from the work image, an error from the design data can be calculated for each edge position. In this embodiment, the error from the design data is calculated for each edge position, but the error may be calculated only for a part of the edge positions by thinning out the edge positions.

<Master image>
FIG. 6 is a diagram illustrating an example of a master image A1 that is held in advance as design data. The master image A1 is a pattern image used for setting feature amounts and comparing contours.

  The master image A1 is created based on a photographed image obtained by photographing a predetermined reference object with the image measuring device 100, for example. Alternatively, a CAD image created by CAD may be used as the master image A1. Here, an example in which a captured image obtained by capturing a predetermined reference object with the image measuring apparatus 100 is used as the master image A1 will be described. By comparing such a master image A1 with a work image obtained by photographing a work, the degree of contour mismatch can be detected.

<Graph display of time series information>
FIG. 7 is a diagram showing an example of the operation when displaying the measurement result in the image measuring apparatus 100 of FIG. 1, and shows an example of a graph display of the time series information associated with the edge position. When the image measuring apparatus 100 is used at a manufacturing site, a plurality of workpieces of the same shape and substantially the same size are usually continuously used in order to continuously measure processed and molded workpieces and perform pass / fail judgment. There are many cases to measure. When measuring workpieces of the same shape and size continuously, once set measurement setting data can be used repeatedly, the user simply sets the workpiece at the measurement position and instructs the execution of the workpiece. The pass / fail judgment can be executed one after another.

  By acquiring the error between each edge position and the design data every time measurement is repeated, the error for each edge position can be acquired in time series. (A) and (b) in the figure are examples showing time series information of errors obtained at this time. This time-series information includes errors for each work image corresponding to the edge position, is created based on a plurality of work images acquired sequentially, and is held in association with the edge position.

  In the example of FIG. 7, the time series information is displayed in a graph with the horizontal axis as the number of measurements and the vertical axis as the error measurement value. Further, in this graph, a line 2 indicating the average value of errors, determination lines 4a and 4b corresponding to the standard deviation σ of errors, and tolerance lines 3a and 3b indicating the upper limit and the lower limit of the tolerance are displayed, respectively. With such a graph display, it is possible to easily identify at which point the error has changed greatly.

  FIG. 7A shows an example in which the measurement accuracy is rapidly deteriorated during the continuous measurement, that is, after the T-th measurement. In such a case, a sudden abnormality may have occurred in the user's manufacturing environment. On the other hand, in the case of FIG. 7B, since there is a large variation in the machining accuracy of the workpiece as a whole, for example, there is a variation in the positioning accuracy of the workpiece during machining, or the machining device itself is stable due to aging There is a possibility that the processed accuracy cannot be maintained.

  FIG. 8 is a diagram showing an example of the operation when displaying the measurement result in the image measuring apparatus 100 of FIG. 1, and shows the frequency distribution for each measurement value associated with the edge position. This figure is an example of a graph display of statistical information, and shows a case where the horizontal axis is the error measurement value, the vertical axis is the frequency, and the appearance frequency of the measurement value is the statistical information.

  In this way, by checking the time series information and frequency distribution of errors, it becomes easy to investigate the timing and cause of defective products. However, simply checking such time-series information does not make it possible to grasp which part of the entire work is particularly defective. That is, it is difficult to evaluate and analyze the error for each part of the workpiece even though the time-dependent information and the frequency distribution alone can confirm the change of the error over time.

  Therefore, in the present embodiment, error statistical information is calculated for each edge position, and the statistical information is superimposed and displayed along the contour of the work image or design data.

<Statistical information overlay on work image>
FIG. 9 and FIG. 10 are diagrams showing an example of the operation at the time of displaying the measurement result in the image measuring apparatus 100 of FIG. 1, and a work image A2 in which dots 1 indicating error statistical information are arranged on the edge is shown. It is shown. The work image A2 is, for example, a photographed image obtained by photographing a work in a low-magnification visual field at a low magnification. In this figure, a photographed image obtained by photographing the work arranged in the detection area 13 at the time of transmitted illumination is shown.

  By analyzing the workpiece image A2 based on the feature amount information of the measurement setting data, it is possible to specify the arrangement state such as the position and posture of the workpiece in the low magnification field of view. Edge extraction of the workpiece image A2 is performed by analyzing the workpiece image A2 based on the arrangement state of the workpiece.

  Specifically, the edge point is detected by analyzing the luminance change of the work image A2. Then, for a plurality of detected edge points, if a geometrical figure such as a straight line or an arc is fitted to these edge points using a statistical method such as a least square method, the outline of the workpiece is obtained as an edge. .

  If an edge position is obtained for a plurality of workpiece images A2 obtained by sequentially photographing a plurality of workpieces of the same shape and substantially the same size, the outline of the workpiece image A2 varies due to the influence of dimensional variations during manufacturing of each workpiece. Occurs.

  In the image measuring apparatus 100 according to the present embodiment, the degree of contour mismatch is represented by dots 1 having different sizes and colors according to the value of statistical information. The error is a parameter indicating the amount of displacement between the edge position of the workpiece image A2 and the corresponding position on the master image. The statistical information is an index indicating the degree of deviation for each edge position, and is composed of error calculation results for a plurality of workpiece images A2. For example, as statistical information, an error average value, error variance value, OK rate, NG rate, error moving average slope, error maximum value, minimum value, and the like are calculated. The NG rate is the rate at which the error exceeds the tolerance.

  The dot 1 is a display object that is displayed in a display mode corresponding to the value of the statistical information, and includes, for example, a circular area whose size and hue are different depending on the value of the statistical information. The dot 1 is arranged along the edge position extracted from the work image A2 or the master image A1. In this example, the dot 1 is arranged on the edge of the work image A2. The dot 1 may be displayed on the edge of the master image A1.

  The user can select various types of statistical information. FIG. 9 shows a display example when the average value of errors is selected as the statistical information, and the dot 1 at the edge position where an error occurs on the average is greatly displayed. On the other hand, FIG. 10 shows a display example when the error variance value is selected, and the dot 1 at the edge position where a large amount of error variance occurs is displayed large. As shown in these figures, the edge position where the dot 1 is displayed may change by switching the statistical information to be displayed.

  In this way, by switching the statistical information to be displayed, the user can check error information according to the characteristics of each statistical information. For example, when the variance value of the error is large, there is a possibility that the workpiece positioning accuracy at the time of machining varies, or that the machining device itself cannot maintain stable machining accuracy due to deterioration over time. . On the other hand, if the inclination of the moving average of the error is confirmed, it is possible to confirm a specific part whose processing accuracy is decreasing with time at a faster speed than other parts. This makes it easy for the user to investigate the cause of the problem and take necessary measures.

  Further, in the present embodiment, when the user designates the edge position P1 in FIG. 9, for example, time-series information as shown in FIG. 7A described above is displayed. Since the edge position P1 has a large average error value, time series information in which a large error continuously occurs is displayed. On the other hand, when the user designates the edge position P2 in FIG. 10, time-series information as shown in FIG. 7B is displayed. The edge position P2 is time-series information with a small average value of errors but a large variance value. In this way, by specifying the edge position that the user is particularly interested in when the statistical information is superimposed and displayed, it is possible to check the change in error over time that cannot be confirmed by the superimposed display of statistical information.

<Thinning display>
FIG. 11 is a diagram showing another example of the operation when displaying the measurement result in the image measuring apparatus 100 of FIG. 1, and shows a case where dots 1 indicating error statistical information are thinned and arranged on the edge. ing. When displaying the dot 1 having a different size or hue according to the value of the statistical information along the edge position, the dot 1 may be displayed in units of pixels. However, in order to easily identify the statistical information or the dot 1, It is desirable to display thinning out. In this thinning display, dots 1 are arranged on the edge at predetermined intervals.

<Control unit>
FIG. 12 is a block diagram illustrating a configuration example of the control unit 20 in the image measurement apparatus 100 of FIG. 1, and illustrates an example of a functional configuration in the control unit 20. The control unit 20 includes a measurement setting data storage unit 21, a position and orientation detection unit 22, an edge extraction unit 23, an image comparison unit 24, an error calculation unit 25, a statistical information calculation unit 26, a statistical information display unit 27, and an edge position designation. The unit 28 and the statistical information specifying unit 29 are configured.

  In the measurement setting data storage unit 21, a master image is stored in advance as measurement setting data. The position and orientation detection unit 22 detects the position and orientation of the workpiece by acquiring the workpiece image from the measurement unit 10 and analyzing the workpiece image based on the feature amount information read from the measurement setting data storage unit 21. The edge extraction unit 23 extracts an edge from the work image based on the detection result by the position and orientation detection unit 22. The image comparison unit 24 compares the workpiece image with the master image read from the measurement setting data storage unit 21 and outputs the comparison result to the error calculation unit 25.

  The error calculation unit 25 calculates an error indicating a displacement amount between the edge position of the work image and the position on the master image corresponding to the edge position based on the comparison result by the image comparison unit 24, and the statistical information calculation unit 26. Output to. The statistical information calculation unit 26 calculates statistical information indicating the degree of deviation for each edge position based on the errors calculated for a plurality of workpiece images, and outputs the statistical information to the statistical information display unit 27.

  The statistical information display unit 27 generates screen data for displaying the statistical information along the edge position in a display mode corresponding to the value, and outputs the screen data to the measurement unit 10. Specifically, the dot 1 indicating the statistical information is displayed along the edge position extracted from the work image or the master image. The dot 1 has a different size and hue depending on the value of the statistical information.

  The edge position designation unit 28 designates an edge position on the work image or the master image based on a predetermined operation input by the user. In the statistical information display unit 27, when an edge position is designated by the edge position designation unit 28, an operation of displaying time series information corresponding to the designated edge position is performed.

  The statistical information designating unit 29 designates statistical information to be displayed based on a predetermined operation input by the user. In the statistical information display unit 27, if the statistical information is specified by the statistical information specifying unit 29, an operation of displaying the specified statistical information along the edge position is performed.

<Statistical information display flow>
Steps S401 to S407 in FIG. 13 are flowcharts showing an example of operations at the time of displaying statistical information in the image measurement apparatus 100 in FIG. The statistical information calculation unit 26 calculates statistical information indicating an error for each edge position based on errors calculated for a plurality of workpiece images (step S401). The statistical information display unit 27 displays the dot 1 indicating the statistical information along the edge position (step S402).

  Next, if there is a predetermined switching operation for changing the statistical information to be displayed, the statistical information display unit 27 changes the statistical information (steps S403 and S404). In addition, when an edge position is designated, the statistical information display unit 27 displays time-series information associated with the edge position in a graph (Steps S405 and S406). The processing procedure from step S403 to step S406 is repeated until the display end is instructed (step S407).

  According to the present embodiment, for a plurality of work images A2, statistical information indicating an error for each edge position is calculated from an error between the edge position of the work image A2 and the position on the master image A1, and along the edge positions. Since it is displayed, the error statistical information can be easily identified for any point on the edge. Therefore, it is possible to easily identify the degree of contour mismatch for a plurality of workpieces.

  Further, statistical information to be displayed along the edge position can be switched by a user operation. Furthermore, by specifying the edge position, it is possible to check time series information of errors associated with the specified edge position.

  In the present embodiment, an example in which the dots 1 having different sizes and hues according to the value of the statistical information are displayed along the edge position has been described. However, in a display mode in which the value of the statistical information can be identified. Any other configuration may be used. For example, the present invention includes a display that displays a histogram having different heights according to the value of statistical information along the edge position.

1 dot 10 measurement unit 11 display 11a display screen 12 movable stage 13 detection area 14a XY position adjustment knob 14b Z position adjustment knob 15 power switch 16 measurement start switch 20 control unit 21 subject image storage unit 22 matching image storage unit 23 contour detection Unit 23a position and orientation detection unit 23b edge detection unit 23c fitting unit 24 contour reference storage unit 25 statistical value calculation unit 26 statistical value display unit 27 position designation unit 31 keyboard 32 mouse 40 housing 41 Z drive unit 42 XY drive unit 43, 44 Image sensor 50 Transmission illumination unit 51 Transmission illumination light source 52 Mirror 53 Optical lens 60 Ring illumination unit 71 Coaxial incident illumination light source 72 Half mirror 80 Light reception lens unit 81, 84, 86 Light reception lens 82 Half mirror 83, 85 Diaphragm 100 Image measuring device A1 Master image A2 Work image

Claims (8)

In an image measuring apparatus that captures a workpiece and acquires a workpiece image, and measures the dimension of the workpiece based on the edge position of the workpiece image.
Edge extraction means for extracting edges from the workpiece image;
Image comparison means for comparing the workpiece image and pre-stored design data;
Based on the comparison result, an error calculating means for calculating an error indicating an amount of displacement between the edge position of the work image and the position on the design data corresponding to the edge position;
Statistical information calculation means for calculating statistical information of the error calculated for a plurality of the work images for each edge position;
An image measurement apparatus comprising: statistical information display means for displaying the statistical information along an edge position extracted from the work image or the design data in a display mode corresponding to the value. A statistical information specifying means for specifying the statistical information to be displayed is provided.
The statistical information calculation means includes, as the statistical information, an average value of the error, a variance value of the error, a ratio at which the error is less than or equal to an allowable error, a ratio at which the error exceeds an allowable error, or a moving average of the error Calculate the slope of
The image measurement apparatus according to claim 1, wherein the statistical information display unit displays designated statistical information along the edge position. An edge position designating means for designating an edge position on the work image or the design data;
The image measurement apparatus according to claim 2, wherein the statistical information display unit displays time series information including the error for each work image corresponding to a specified edge position.   The image measurement apparatus according to claim 1, wherein the statistical information display unit displays dots of different colors along the edge position according to the value of the statistical information.   The image measurement apparatus according to claim 1, wherein the statistical information display unit displays dots having different sizes according to the value of the statistical information along the edge position.   The image measurement apparatus according to claim 1, wherein the statistical information display unit displays a histogram having different heights along the edge position according to a value of the statistical information. In an image measurement method for capturing a workpiece by capturing a workpiece and measuring the dimension of the workpiece based on an edge position of the workpiece image,
An edge extraction step of extracting an edge from the workpiece image;
An image comparison step for comparing the work image and pre-stored design data;
Based on the comparison result, an error calculating step for calculating an error indicating an amount of displacement between the edge position of the work image and the position on the design data corresponding to the edge position;
Statistical information calculation step for calculating statistical information of the error calculated for a plurality of the work images for each edge position;
An image measurement method comprising: a statistical information display step for displaying the statistical information along the edge position extracted from the work image or the design data in a display mode corresponding to the value. In a program for an image measuring device for capturing a workpiece to acquire a workpiece image and measuring the dimension of the workpiece based on the edge position of the workpiece image,
An edge extraction procedure for extracting an edge from the workpiece image;
An image comparison procedure for comparing the work image and pre-stored design data;
Based on the comparison result, an error calculation procedure for calculating an error indicating an amount of displacement between the edge position of the work image and the position on the design data corresponding to the edge position;
Statistical information calculation procedure for calculating statistical information of the error calculated for a plurality of the work images for each edge position;
A program for an image measuring apparatus, which causes a statistical information display procedure to display the statistical information along an edge position extracted from the work image or the design data in a display mode corresponding to the value. .

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